How would you test AWS VPC, Subnets, and Security Groups?

Answers use simple, clear English.

Quick interview answer

Test AWS VPC, Subnets, and Security Groups with unit checks for the happy path, integration tests for real I/O boundaries, and load/chaos checks so regressions show up before prod. Core idea: VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

Detailed answer

Interview answer for testing AWS VPC, Subnets, and Security Groups: 1) Unit: isolate the pure logic behind AWS VPC, Subnets, and Security Groups with deterministic fixtures. 2) Integration: exercise real timers/I/O/network boundaries the way production does. 3) Load & soak: prove the event path still meets SLOs under concurrency. 4) Failure injection: break dependencies and assert recovery/backpressure. Best practices to include: Least privilege SG; VPC endpoints for S3/ECR; flow logs. Call out mistakes: 0.0.0.0/0 on SSH SG; databases in public subnets. Parent context: VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

Full explanation

Interviewers want a test strategy, not “I would write tests.” Tie each layer back to how AWS VPC, Subnets, and Security Groups fails: correctness, latency, and starvation. VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless. Private workloads without public IPs.

Follow-up questions

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Parent context — AWS VPC, Subnets, and Security Groups

VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

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